Objective.



'0. H. FLO'RIAK OBJECTIVE. APPLICATION FILED JUNE 1*, 1913.

1,122,895, Patented "Dec. 29,1914;

ua; 0 Inventor 9 6mm M,

. 777 gum-1 my WiW UNITED STATES PATENT OFFICE.

CHARLES HENRI FLORIAN, OF PARIS, FRANCE, ASSIGNOR TO SOGIEI'E ANONYMEDES ETA BLISSEMENTS LACOUR-BERTHIOT, OF

PARIS. FRANCE.

OBJECTIVE.

Application filed June 4, 1913.

To all 207mm it may concern:

Be it known that I, CHARLES HENRI -phragm. The'front group comprises-twoseparated lenses the whole of which presents a negative sphericalaberration. The second group is constituted by three combined lensespresenting a notable positive aberration which compensates theaberration of the first group. p

The accompanying drawing, given by Way of example only, illustratesdiagrammatically the new objective.

The first lens L, of the front group is highly convex at the front andslightly convex or even plane at the rear. The second lens is biconcave;the film of air be-,

tween these two lenses is therefore of diver ent character.

he index of refraction of the first lens is greater than that of thesecond lens:

n, n, On the other hand, these indices satisfy the inequality:

An, An, n,1 'n,-1

An designating the difference of the indices for the two spectral raysbetween which the achromatism is to be corrected.

The group of the two lenses L L may bea focal or even divergent; it isovercorrected from the spherical as to present a negative aberration.

he second group constitutes a seminormal combination; itcomprises twocon-.

'verged elements L L separated by a divergent element L.. These threeelements Specification of Letters Patent.

Wh1Cl1 it was endeavored aberration so Patented Dec. 29, 1914. SerialNo. 771,691.

L, L, L are drawing. r

The indices of refraction satisfy the following conditions:

If we consider we must have:

the whole of the elements,

and

An, An, A An, An, n,1 n,1 n -1 02 -1 vi -1 Contrary to the systemgenerally used to correct, the present system constituted by the lensesL 4 5 possesses a notable positive spherical aberration adapted tocompensate the negative aberration of the first group of lenses.

The film of air (5 and the surface 0 add their negative aberrationswhich are compensated by the whole of the convergent surfaces of theobjective. By this fact and by the'disposition of the elements of thisobjective, the corrections are rendered easy without being compelled toresort to curved surfaces such as in the ordinary systems. t the sametime, by reason principally of the diminution of the curvatures, thezonal aberrations are considerably diminished.

The new objective is principally intended for photography and projectionpurposes; it is particularly suitable for taking instantaneous or rapidviews or with a small light in which considerable sharpness is desired.It is also suitable for projections or reproductions in which the sameconditions must be realized. It is also advantageouswhen it is desiredto avoid heating in an exaggerated manner the object to be projected,film or plate. The new objective is therefore particularly suitable forthe two reverse operations of the kinematography.

put together, as shown in the way of example, the following values inaybe indicated: I m==1.6l28

only given by way of example and may vary insufficiently large limits aswell as the relative openlng', provided the general conditions set forthare observed.

Claimsz 1. An objective formed of two groups of lenses, the first groupcomprising two sepatwo lenses and a group of F being variation m ratedlenses the whole of which presents a negative spherical aberration, thesecon group comprising three combined lenses presenting a notablepositive aberration which compensates the negative aberration of thefirst group.

. 2. An objective comprising a group of three lenses,'the first, thefifth, the secon the fourth and the third lens having indices ofrefraction of decreasing values, that of the firsta'nd that of the fifthlens may at the limit be equal, while the quotients of the variations ofthe indices between the spectral rays for which the achromatism iscorrected, an

the indices minus one unit, decrease from the third to the first, to thefifth, to the fourth and to the secondlens, these quotients ma at thelimit be equal for the first and the fifth lens. a

The foregoing specification of my objective signed by me this tenth dayof May 1913.

CHARLES HENRI FLORIAN. "Witnesses:

HANSON C. Coxn, RENE TRIP-Ion

